Electrolytic Cells utilizes electrical energy to create chemical energy

chemical potential energy electrical potential energy galvanic/Voltaic cell electrolytic cell (battery needed) chemical rxns can produce electricity in galvanic/Voltaic cells (spontaneous rxn - exothermic) OR electrical energy used to carry out chemical reactions in electrolytic cell (non-spont rxn - endothermic)

spontaneous reactions: (galvanic/Voltaic cell) e - flow: (-) ANODE to (+) CATHODE generates own power produces energy – exo anode: higher metal on table J cathode: lower metal on table J non-spontaneous reactions: (electrolytic cell) e - flow: (+) ANODE to (-) CATHODE needs power source: battery consumes energy – endo anode: lower metal on table J cathode: higher metal on table J

two types of electrolytic cells 1. fused salt cells – used to purify metals (fused means melted!) 2. electroplating cells – designed to cover a surface with metal so will have specific properties

Electroplating electroplating: putting one metal on top of another move desired coating (anode) onto object (cathode) to be plated solution contains ions (Cu +2 ) of element (Cu) to be plated

An Ox ate a Red Cat anode: electrode at which oxidation occurs cathode: electrode at which reduction occurs electrode polarity opposite than galvanic cell! –anode is POSITIVE –cathode is NEGATIVE

A POX A POX on Electrolytic Cells Anode – Positive – Oxidation electrolytic cell: polarity determined by outside power supply –anode is attached to (+) terminal –cathode is attached to (-) terminal

Can Cu be plated onto Al? Al above Cu in Table J –reaction will not happen spontaneously so… –external energy source (power supply or battery) needed to force reaction to occur (plating Cu on Al) cathode (-): object to be plated (must be more reactive than anode – higher on table J) anode (+): made of metal want to plate on object (must be less reactive than cathode – lower on table J) solution: contains ions of metal to be plated (anode)

Battery (+) (-) anode: where oxidation happens Cu  Cu e - cathode: obj being plated (Al) - where reduction happens Cu e -  Cu Note: just moving Cu around (+) (-) Cu(s) Cu +2 SO 4 -2

In summation: galvanic or Voltaic galvanic or Voltaic cells: –use spontaneous SR rxn to produce flow of electrons (electricity) –exothermic –electrons flow from anode (oxidized substance) to cathode (reduced substance) electrolytic cells: –use flow of electrons (electricity) to force non-spontaneous rxn to occur –endothermic –electrons flow from anode (oxidized substance) to cathode (reduced substance)